I did see something mentioned about the alarm chirp in the code but I haven't been able to test it on a non-alarm equipped car yet.

Anyways, if you want to try and see if it works, to enable this in the menu on the iDrive, you can find it in the code here:

HU_CIC -> 3000 -> ACOUSTICAL_LOCK_CONFIRM -> set from nicht_aktiv to aktiv (at least I'm figuring that this has to be done on the non-alarm equipped car since I do have alarm and it says 'aktiv' with me ).